Apparatus and method for subframe arrangement

ABSTRACT

One embodiment is directed to a method comprising generating at least one symbol of a subframe for control information based on a first subcarrier spacing; generating at least one data symbol of the subframe based on a second subcarrier spacing; and transmitting the subframe comprising the at least one symbol for control information and at least one data symbol. Another embodiment is directed to a method comprising receiving a subframe comprising at least one symbol for control information and at least one data symbol; decoding the at least one symbol for control information based on a first subcarrier spacing; and obtaining from the decoded at least one symbol information regarding a second subcarrier spacing used on the at least one data symbol.

RELATED APPLICATION

This application was originally filed as Patent Cooperation TreatyApplication No. PCT/IB2017/055739 filed Sep. 21, 2017 which claimspriority benefit to U.S. Provisional Patent Application No. 62/402,934,filed Sep. 30, 2016.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to and claims the benefit and priority ofU.S. Provisional Patent Application No. 62/402,934, filed Sep. 30, 2016,the entirety of which is hereby incorporated herein by reference.

TECHNICAL FIELD

The present application relates generally to an apparatus and a methodfor novel subframe arrangement to allow dynamic scheduling betweendifferent numerologies.

BACKGROUND

This section is intended to provide a background or context to theinvention that is recited in the claims. The description herein mayinclude concepts that could be pursued, but are not necessarily onesthat have been previously conceived, implemented or described.Therefore, unless otherwise indicated herein, what is described in thissection is not prior art to the description and claims in thisapplication.

Third generation partnership project (3GPP) 5^(th) generation (5G)technology is a new generation of radio systems and network architecturethat can deliver extreme broadband and ultra-robust, low latencyconnectivity. 5G can improve the telecommunication services offered tothe end users, and help support massive machine-to-machine (M2M)communications. 5G is also expected to increase network expandability upto hundreds of thousands of connections. The signal technology of 5G isanticipated to be improved for greater coverage as well as spectral andsignaling efficiency.

A study item has been established in 3GPP for 5G new radio (NR) physicallayer design. An objective of the study item is to identify and developtechnology components needed for NR systems being able to use anyspectrum band ranging at least up to 100 GHz. The goal is to achieve asingle technical framework addressing all usage scenarios, requirementsand deployment scenarios. 5G NR provides support for multiplenumerologies. It has been agreed that forward compatibility of NR shallensure smooth introduction of future services and features with noimpact on the access of earlier services and user equipments (UEs).Hence, multiplexing different numerologies within a same NR carrierbandwidth (from the network perspective) needs to be supported.Frequency division multiplexing (FDM) and/or time division multiplexing(TDM) can be considered.

Downlink (DL) control information (DCI) transmitted by evolved NodeB(eNB) is used e.g. for conveying DL and uplink (UL) schedulinginformation to UE. For 5G NR network, a scheme for conveying DCI formultiple numerologies within an NR carrier needs to be designed.

SUMMARY

According to a first embodiment, a method can include generating atleast one symbol of a subframe for control information based on a firstsubcarrier spacing; generating at least one data symbol of the subframebased on a second subcarrier spacing; and transmitting the subframecomprising the at least one symbol for control information and at leastone data symbol.

According to a second embodiment, a method can include receiving asubframe comprising at least one symbol for control information and atleast one data symbol; decoding the at least one symbol for controlinformation based on a first subcarrier spacing; and obtaining from thedecoded at least one symbol information regarding a second subcarrierspacing used on the at least one data symbol.

According to third and fourth embodiments, an apparatus can includemeans for performing the method according to the first and secondembodiments respectively, in any of their variants.

According to fifth and sixth embodiments, an apparatus can include atleast one processor and at least one memory including computer programcode. The at least one memory and the computer program code can beconfigured to, with the at least one processor, cause the apparatus atleast to perform the method according to the first and secondembodiments respectively, in any of their variants.

According to seventh and eighth embodiments, a computer program productmay encode instructions for performing a process including the methodaccording to the first and second embodiments respectively, in any oftheir variants.

According to ninth and tenth embodiments, a non-transitory computerreadable medium may encode instructions that, when executed in hardware,perform a process including the method according to the first and secondembodiments respectively, in any of their variants.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of example embodiments of the presentinvention, reference is now made to the following descriptions taken inconnection with the accompanying drawings in which:

FIG. 1 illustrates resource block (RB) partitions for differentnumerologies in accordance with an example embodiment of theapplication.

FIG. 2 illustrates downlink signal generation assuming three differentnumerologies in accordance with an example embodiment of theapplication.

FIG. 3 illustrates subframe structures in accordance with exampleembodiments of the application.

FIGS. 4a and 4b illustrate subcarrier spacing adaptation andcorresponding blind detection in accordance with example embodiments ofthe application.

FIGS. 5a and 5b illustrate flowcharts in accordance with exampleembodiments of the application.

FIG. 6 illustrates a simplified block diagram of example apparatusesthat are suitable for use in practicing various example embodiments ofthis application.

DETAILED DESCRIPTION

3GPP considers 15 kHz and scale factors N=2^(n), n∈[ . . . , −2, −1, 0,1, 2, . . . ] for subcarrier spacing as the baseline design assumptionfor the NR numerology. For the numerology with 15 kHz and largersubcarrier spacing (SCS), 1 mini-second (ms) alignment is supported. Ithas been agreed that in one carrier when multiple numerologies are timedomain multiplexed, resource blocks (RBs) for different numerologies arelocated on a fixed grid relative to each other. For subcarrier spacingof 2^(n)×15 kHz, the RB grids are defined as the subset/superset of theRB grid for subcarrier spacing of 15 kHz in a nested manner in thefrequency domain. FIG. 1 shows example RB partitions for differentnumerologies in accordance with an example embodiment of theapplication, where f₀ denotes the smallest possible subcarrier spacing,such as for example, 15 kHz in the 5G baseline design, or in some otherscenario, 3.75 kHz.

The above agreements indicate that multiple numerologies need to besupported within the same NR carrier bandwidth (BW). On the other hand,based on the current working assumptions, NR numerology scaling is basedon 15 kHz baseline design scaled by a factor of N=2^(n), n∈[ . . . , −2,1, 0, 1, 2, . . . ]. In an example embodiment, one numerology is definedat least by a cyclic prefix (CP) duration and a subcarrier spacing of anorthogonal frequency division multiplexing (OFDM) system. As an example,downlink signal assuming three different CP-OFDM numerologies can begenerated as depicted in FIG. 2 for n=0, 1, 2, where the clock rates,OFDM symbol durations (Ts), the (inverse) fast Fourier transform((I)FFT) sizes, maximum BW allocations, numbers of symbols per subframe,subframe lengths, CP lengths and CP overhead percentages for subcarrierspaces of 15 KHz, 30 kHz and 60 kHz are listed, respectively. WOLA inFIG. 2 refers to weighted-overlap-and-add windowing technique, a popularimplementation adopted in various communication systems such as forexample, 3GPP long term evolution (LTE).

Rationale for using different numerologies within the same band istypically justified by providing simultaneous support for both mobilebroadband (MBB) and ultra-reliable and ultra-low-latency (URLLC)services. The latter service calls for short symbols to enable lowlatency whereas MBB service may require wide area coverage support. Inabove example numerology set illustrated in FIG. 2, MBB would operateusing 15 kHz subcarrier spacing while URLLC could operate using 60 kHzsubcarrier spacing.

In LTE, physical downlink control channel (PDCCH) or enhanced physicaldownlink control channel (ePDCCH) carries DCI, which may includeresource assignment and other control information for a UE or group ofUEs. Each (e)PDCCH is transmitted using one or more control channelelements (CCE). Different (e)PDCCH sizes with different CCE aggregationlevels (comprising 1, 2, 4 or 8 CCEs, respectively) are supported in LTErelease 8 (Rel-8).

UE needs to decode all possible (e)PDCCH sizes and locations in order toact on those messages with correct cyclic redundancy check (CRC)scrambled with a UE identity. Carrying out such blind decoding of allpossible combinations of (e)PDCCH sizes and locations in every subframewould lead to excessive power consumption and processing timerequirements at the UE side as well as increased probability of falseUL/DL grant detection. In order to limit the number of blind decodingattempts, LTE system has adopted such an approach where only a limitedset of CCE locations where a (e)PDCCH may be placed is defined for eachUE (this is made at the expense of (e)PDCCH scheduling flexibility). Thelimited CCE set is considered as a (e)PDCCH search space, which isdivided into common part with 6 (e)PDCCH candidates and dedicated partwith 16 candidates, respectively. These candidates need to be decodedtwice as there are two size options defined for the (e)PDCCH both incommon and in dedicated search space. This gives the maximum number of(e)PDCCH blind decoding attempts as 44, which the LTE Rel-8 UE isrequired to carry out in any subframe. UE's (e)PDCCH blind detectioncapability increases linearly with the number of DL component carriers(CCs) supported in LTE carrier aggregation (i.e. Rel-10 and beyond).

Downlink control signaling principles defined in LTE form the baselinealso for NR. On the other hand, conventional LTE has been designed tosupport just one numerology. It is not fully straightforward to extendthe current DL control signaling framework to support also scenarioswith multiple numerologies. In principle, each numerology option willincrease the UE's DCI detection burden linearly. Moreover, the UE maynot be able to decode multiple numerologies simultaneously with currentdelay budget and current hardware. A design for supporting multiplenumerologies without additional hardware at the receiver is desired.

In an example embodiment, a subframe and DCI arrangement is proposed toenable network element (NE) such as for example, an eNB, to scheduledifferent numerology options dynamically without an UE requirement todecode multiple numerologies simultaneously. Numerology can be allocatedin subframe basis via NE scheduling.

In an example embodiment, a subframe containing DCI includes at leastone symbol with predetermined subcarrier spacing regardless of thesubcarrier spacing used on the rest of the subframe. For example, when15 kHz subcarrier spacing is used for data symbol of a subframe, the atleast one symbol containing DCI may be transmitted/received by using 60kHz subcarrier spacing. In an example embodiment, the at least onesymbol may be the first symbol(s) of the subframe. The number of symbolswith predetermined subcarrier spacing depends on the subframe lengthand/or subcarrier spacing used for data.

In an example embodiment, the DCI included in the at least one symbol ofsubframe contains at least information about subcarrier spacing used inthe rest of the subframe.

In an example embodiment, the at least one symbol containing DCI (or atleast part of DCI) may be transmitted/received by using a smaller FFTthan data symbols. A UE may adjust it receiver bandwidth in such that asmaller receiver bandwidth is used to receive the at least one symbol.

The example of subframe structures in accordance with various exampleembodiments of the application for 15 and 60 kHz data subcarrier spacingare shown in FIG. 3. It should be noted that the term “subframe” is justan example of possible name for the considered time unit. For example,“slot” or ‘NR subframe” could be equally applicable terms. Regardless ofthe numerology selected for data channel, the subcarrier spacing of thefirst symbol is 60 kHz in this example. FIG. 3 presents examplebidirectional subframe structures with DL data portion (symbols denotedby “DL”) according to the application. The symbol denoted by “GP” refersto guard period and the symbol denoted by “UL” refers to uplink controlor/and data symbol of the subframe. Invention can be applied also forother subframe types like DL only, UL only or bi-directional subframewith UL data portion. In the various subframe types with different TDMcombinations of DL control (DCI), DL data, GP and UL control or/anddata, under the principle of numerology scaling based on scalingparameter (N=2^(n)), numerology can be selected separately for eachportion.

With data symbols of 15 kHz subcarrier spacing, the DCI can be detectedby using a smaller FFT size compared with that used for data symbols,for example, 512 FFT for DCI symbol and 2048 FFT for data symbol.Another option is to use the same FFT size for both control and datasymbols, which corresponds to approach for having larger bandwidth forcontrol channel Note that the numbers of DCI symbols in 301 and 303 are4 and 1, respectively, due to the different subframe lengths, eventhough 15 kHz SCS is used for DL data in both cases.

In the example subframe structures of FIG. 3, there is UL portion in theend of bi-directional subframes (301, 302, 303). It may be used forconveying Physical uplink control channel (PUCCH) carrying differentuplink control information (UCI) types such as hybrid automatic repeatrequest (HARQ) feedback, scheduling request, channel station information(CSI) feedback and their combinations via PUCCH. Additionally, it may bepossible to multiplex PUCCH with sounding reference signal (SRS) withinthe UL control symbol(s). In an example embodiment, the UL portion maymultiplex UL control and UL data. The subcarrier spacing for UL portionvaries in examples 301, 302, 303. The SCS may be selected independentlyfrom the subcarrier spacing applied for data part (and/or DL controlpart). For example, in 303, subcarrier spacing for UL portion is 60 kHzwhereas DL data part utilizes 15 kHz subcarrier spacing. Another examplein 301 illustrates the scenario where both DL data and UL portionutilize the same subcarrier spacing (15 kHz). Another option for ULportion arrangement in 301 would be to have four UL control symbols with60 kHz subcarrier spacing (this example is not shown). With data symbolsof 15 kHz subcarrier spacing, the UL control symbols can be processed byusing a smaller FFT size compared with that used for data symbols, forexample, 512 FFT for UL control symbols and 2048 FFT for data symbol.Another option is to use the same FFT size for both control and datasymbols, which corresponds to approach for having larger bandwidth forcontrol channel.

UE blind detection operation is illustrated in FIGS. 4a and 4b inaccordance with various example embodiments of the application for 15and 60 kHz data subcarrier spacing. Similar to FIG. 3, regardless of thenumerology selected for data channel, the subcarrier spacing of the DCIsymbol is 60 kHz. The first one or more control symbols of a subframeconveys the information on the subcarrier spacing for remaining blocksof the subframe. In an example embodiment, if subcarrier spacing is 15kHz for data and subframe length is 0.5 ms or approximately 0.5 ms (e.g.the subframe structure 301 of FIG. 3), then (e)PDCCH blind detection isperformed based on the first four symbols (each with 60 kHz SCS) of thesubframe, as illustrated in FIG. 4a . In another example embodiment, ifsubcarrier spacing is 60 kHz for data (e.g, the subframe structure 302of FIG. 3), or subframe length is 0.125 ms or approximately 0.125 ms(e.g, the subframe structure 303 of FIG. 3), then (e)PDCCH blinddetection is performed based on the four DCI symbols each from one offour subframes, as illustrated in FIG. 4 b.

FIGS. 5a and 5b illustrate flowcharts in accordance with various exampleembodiments of the application. In the example of FIG. 5a , a networkelement, such as for example, an evolved NodeB (eNB), generates at leastone symbol of a subframe for control information based on a firstsubcarrier spacing at step 501. The first subcarrier spacing may bepredetermined or configured by standard specification, manufacturer,network operator, or dynamic signaling (such as higher layer signaling).The NE also generates at least one data symbol of the subframe based ona second subcarrier spacing at step 503. The first and the secondsubcarrier spacing may be same or different. The control informationcarried by the at least one symbol for control information contains atleast information regarding the second subcarrier spacing. This may beconveyed e.g. in the form of common DCI, or a separate signalmultiplexed in the resource elements of the at least one symbol. At step505 NE transmits the subframe comprising the at least one symbol forcontrol information and the at least one data symbol.

In the example of FIG. 5b , a user equipment receives a subframecomprising at least one symbol for control information and at least onedata symbol at step 502. At step 504, the UE decodes the at least onesymbol for control information based on a first subcarrier spacing. Thefirst subcarrier spacing may be predetermined or configured by standardspecification, manufacturer, network operator, or dynamic signaling(such as higher layer signaling). The UE obtains information regarding asecond subcarrier spacing that is used on the at least one data symbol,from the decoded at least one symbol for control information at step506. The first and the second subcarrier spacing may be same ordifferent.

Reference is made to FIG. 6 for illustrating a simplified block diagramof various example apparatuses that are suitable for use in practicingvarious example embodiments of this application. In FIG. 6, a NE 601, isadapted for communication with a UE 611. The UE 611 includes at leastone processor circuitry 615, at least one memory (MEM) 614 coupled tothe at least one processor circuitry 615, and a suitable transceiver(TRANS) 613 (having a transmitter (TX) and a receiver (RX)) coupled tothe at least one processor circuitry 615. The at least one MEM 614stores a program (PROG) 612. The TRANS 613 is for bidirectional wirelesscommunications with the NE 601.

The NE 601 includes at least one processor circuitry 605, at least onememory (MEM) 604 coupled to the at least one processor circuitry 605,and a suitable transceiver (TRANS) 603 (having a transmitter (TX) and areceiver (RX)) coupled to the at least one processor circuitry 605. Theat least one MEM 604 stores a program (PROG) 602. The TRANS 603 is forbidirectional wireless communications with the UE 611. The NE 601 may becoupled to one or more cellular networks or systems, which is not shownin this figure.

As shown in FIG. 6, the NE 601 may further include a multiplenumerologies control unit 606. The unit 606, together with the at leastone processor circuitry 605 and the PROG 602, may be utilized by the NE601 in conjunction with various example embodiments of the application,as described herein.

As shown in FIG. 6, the UE 611 may further include a multiplenumerologies process unit 616. The unit 616, together with the at leastone processor circuitry 615 and the PROG 612, may be utilized by the UE611 in conjunction with various example embodiments of the application,as described herein.

At least one of the PROGs 602 and 612 is assumed to include programinstructions that, when executed by the associated processor, enable theelectronic apparatus to operate in accordance with the exampleembodiments of this disclosure, as discussed herein.

In general, the various example embodiments of the apparatus 611 caninclude, but are not limited to, cellular phones, personal digitalassistants (PDAs) having wireless communication capabilities, portablecomputers having wireless communication capabilities, image capturedevices such as digital cameras having wireless communicationcapabilities, gaming devices having wireless communication capabilities,music storage and playback appliances having wireless communicationcapabilities, Internet appliances permitting wireless Internet accessand browsing, as well as portable units or terminals that incorporatecombinations of such functions.

The example embodiments of this disclosure may be implemented bycomputer software or computer program code executable by one or more ofthe processor circuitries 605, 615 of the NE 601 and the UE 611, or byhardware, or by a combination of software and hardware.

The MEMs 604 and 614 may be of any type suitable to the local technicalenvironment and may be implemented using any suitable data storagetechnology, such as semiconductor-based memory devices, flash memory,magnetic memory devices and systems, optical memory devices and systems,fixed memory and removable memory, as non-limiting examples. Theprocessor circuitries 605 and 615 may be of any type suitable to thelocal technical environment, and may include one or more of generalpurpose computers, special purpose computers, microprocessors, digitalsignal processors (DSPs) and processors based on multi-core processorarchitecture, as non-limiting examples.

Without in any way limiting the scope, interpretation, or application ofthe claims appearing below, a technical effect of one or more of theexample embodiments disclosed herein may be flexible multiplexing ofdifferent numerologies for control information signaling with capabilityto limit UEs' blind detection efforts. It also allows UE to save energysince there is no need of parallel processing and control informationcan be received by using smaller FFT/BW.

Embodiments of the present invention may be implemented in software,hardware, application logic or a combination of software, hardware andapplication logic. The software, application logic and/or hardware mayreside on an apparatus such as a user equipment, an eNB or other mobilecommunication devices. If desired, part of the software, applicationlogic and/or hardware may reside on a network element 601, part of thesoftware, application logic and/or hardware may reside on a UE 611, andpart of the software, application logic and/or hardware may reside onother chipset or integrated circuit. In an example embodiment, theapplication logic, software or an instruction set is maintained on anyone of various conventional computer-readable media. In the context ofthis document, a “computer-readable medium” may be any media or meansthat can contain, store, communicate, propagate or transport theinstructions for use by or in connection with an instruction executionsystem, apparatus, or device. A computer-readable medium may comprise anon-transitory computer-readable storage medium that may be any media ormeans that can contain or store the instructions for use by or inconnection with an instruction execution system, apparatus, or device.

It is also noted herein that while the above describes exampleembodiments of the invention, these descriptions should not be viewed ina limiting sense. Rather, there are several variations and modificationswhich may be made without departing from the scope of the presentinvention. For example, the described example embodiments may use SCS 15kHz and 60 kHz just as examples with different SCS. The idea scales toany scenario having separate SCS for control and data. There may also bemore than two SCS options available. For example, there could be fournumerology options, and the selected one(s) is indicated via the atleast one symbol for control information. Generally speaking theselection may be seen as a subframe (slot) format for certain timeperiod, and the control information can indicate the combination ofnumerologies selected for different portions of the subframe (slot),including optionally also the subframe (slot) length. Moreover, althoughthe arrangement proposed above mainly focuses on the scenario wheremultiple numerologies are mixed in TDM manner, the principle can beapplied also in the scenario of FDM multiplexing between differentnumerologies. In this case, the principle can be applied in the sub-bandbased manner.

Further, the various names and terms are not intended to be limiting inany respect Such as for example, “subframe” herein is a general term toindicate regular scheduling unit in time and it may be identified by anysuitable names.

If desired, the different functions discussed herein may be performed ina different order and/or concurrently with each other. Furthermore, ifdesired, one or more of the above-described functions may be optional ormay be combined. As such, the foregoing description should be consideredas merely illustrative of the principles, teachings and exampleembodiments of this invention, and not in limitation thereof.

We claim:
 1. An apparatus, comprising: at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: generate at least one symbol of a subframe for control information based on a first subcarrier spacing; generate at least one data symbol of the subframe based on a second subcarrier spacing, wherein the second subcarrier spacing is different than the first subcarrier spacing; and transmit the subframe comprising the at least one symbol for control information and at least one data symbol.
 2. The apparatus according to claim 1, wherein the number of the at least one symbol for control information depends on at least one of the length of the subframe and the second subcarrier spacing.
 3. The apparatus according to claim 1, wherein the control information contains information about the second subcarrier spacing.
 4. The apparatus according to claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: when transmitting the subframe, transmit the at least one symbol for control information by using fast Fourier transform with a size smaller than that of the at least one data symbol.
 5. The apparatus according to claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to: when transmitting the subframe, transmit the at least one symbol for control information by using fast Fourier transform with a size same as that of the at least one data symbol but with a bandwidth larger than that of the at least one data symbol.
 6. The apparatus according to claim 1, wherein the first subcarrier and the second subcarrier are located on different sub-bands.
 7. An apparatus, comprising: at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: receive a subframe comprising at least one symbol for control information and at least one data symbol; decode the at least one symbol for control information based on a first subcarrier spacing; and obtain from the decoded at least one symbol information regarding a second subcarrier spacing used on the at least one data symbol, wherein the second subcarrier spacing is different than the first subcarrier spacing.
 8. The apparatus according to claim 7, wherein the number of the at least one symbol for control information depends on at least one of the length of the subframe and the second subcarrier spacing.
 9. The apparatus according to claim 7, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: when receiving the subframe, receive the at least one symbol for control information by using fast Fourier transform with a size smaller than that of the at least one data symbol.
 10. The apparatus according to claim 7, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: when receiving the subframe, receive the at least one symbol for control information by using fast Fourier transform with a size same as that of the at least one data symbol but with a bandwidth larger than that of the at least one data symbol.
 11. The apparatus according to claim 7, wherein the first subcarrier and the second subcarrier are located on different sub-bands.
 12. A method, comprising: generating at least one symbol of a subframe for control information based on a first subcarrier spacing; generating at least one data symbol of the subframe based on a second subcarrier spacing, wherein the second subcarrier spacing is different than the first subcarrier spacing; and transmitting the subframe comprising the at least one symbol for control information and at least one data symbol.
 13. The method according to claim 12, wherein the control information contains information about the second subcarrier spacing.
 14. The method according to claim 12, wherein the first subcarrier spacing and the second subcarrier spacing are different.
 15. A method, comprising: receiving a subframe comprising at least one symbol for control information and at least one data symbol; decoding the at least one symbol for control information based on a first subcarrier spacing; and obtaining from the decoded at least one symbol information regarding a second subcarrier spacing used on the at least one data symbol, wherein the second subcarrier spacing is different than the first subcarrier spacing.
 16. The method according to claim 15, wherein receiving the subframe comprising: receiving the at least one symbol for control information by using fast Fourier transform with a size smaller than that of the at least one data symbol.
 17. The method according to claim 15, wherein the first subcarrier spacing and the second subcarrier spacing are different.
 18. A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least: receiving a subframe comprising at least one symbol for control information and at least one data symbol; decoding the at least one symbol for control information based on a first subcarrier spacing; and obtaining from the decoded at least one symbol information regarding a second subcarrier spacing used on the at least one data symbol, wherein the second subcarrier spacing is different than the first subcarrier spacing. 